A direct type tire air pressure detecting device is known conventionally. In the direct type air pressure detecting device, a sensor transmitter provided with a pressure sensor and the like is attached to a wheel side at which a tire is mounted. When a detection result of the sensor is transmitted from the sensor transmitter, a vehicle body side system receives the detection result and detects a tire air pressure.
In such a direct type tire air pressure detecting device, it is necessary to specify to which wheel the detection result of the tire air pressure transmitted form the sensor transmitter belongs. For this reason, in the vehicle body side system, a mount position of each wheel, that is, a wheel position indicating at which position of the vehicle the sensor transmitter is attached and individual identification information (hereinafter referred to as ID information) are linked.
For example, this linking is made by a manual operation of an operator by inputting the ID information of each wheel into the vehicle body side system or by bilateral communication between the sensor transmitter and the vehicle body side system by using a trigger device (for example, refer to patent literature 1).